Sediments quality assessment in terms of single and integrated indices from Romanian MONITOX network (2019 – 2020)

Abstract

The assessment of sediments quality from Romanian part of MONITOX Network was performed using both single indices - Single Ecological Risk Index (ErMe), Contamination Factor (CF Me), Enrichment Factor (EF Me), Geoaccumulation Index (Igeo Me) - and integrated indices - Ecological Risk Index (RI), Global Pollution Index (PLI), Nemerow Pollution Index (PI N), Degree of Contamination (mCd), Probability of Toxicity (MERMQ), Contamination Security Index (CSI) - considering the heavy metals concentrations. The sediments were collected in 2019 and 2020 from 32 sampling points in the system of Danube river – Danube Delta - Black Sea, as follows: Lower Danube RO-BG (1), Lower Danube RO (10), Lower Prut RO-MD border (2), Danube Delta RO-UA border (7), Danube Delta –RO (2), Black-Sea area-RO (10). The selected heavy metals investigated in this work by ICP-MS technique are: Cd, Cr, Cu, Pb, Zn, Mn. For the evaluation of defined indices, the standard quality levels and background concentrations corresponding to the selected heavy metals were used. At the individual and integrated levels, it was observed an annual decreasing trend. The sediments from the Black Sea area are much less contaminated with heavy metals than those from the Lower Danube (Romania), attributed to the historical pollution resulting from anthropogenic activities. CSI – an index that includes the biological effects – shows values indicating that in 2019 and 2020 the sediments were unpolluted with heavy metals; however, the CSI value for both years (0.402 for 2019 and 0.398 for 2020) is very close to 0.5, the limit which separates the two quality classes/risk levels for heavy metals in sediments - uncontaminated and very low contaminated.